1. Field of the Invention
The present invention relates to a connector equipped with a valve such as those used for evaporation tubes in fuel supply systems of automobiles.
2. Discussion of the Related Art
In order to prevent fuel vapor gas generated in gasoline fuel tanks of automobiles from being discharged into the atmosphere, a vapor discharge prevention mechanism that causes the vapor to be adsorbed in the canister is widely used. In this type of vapor discharge prevention mechanism, the evaporation tube connecting the fuel tank and the canister uses a one-way or check valve to maintain an appropriate pressure in the fuel tank.
In this type of evaporation tube, rubber hoses are connected to the ends of the one-way valve or check valve. The end of the rubber hose on a first side is connected, e.g., to a connecting pipe connected to a roll-over valve disposed on the fuel tank. A second end of the rubber hose on a second side is connected to a connecting pipe on the canister side. Transpiration of gasoline from the fuel supply pipe must be kept at a minimum so resin tubes are sometimes used in place of rubber hoses. When resin tubes are used, the connections between the resin tubes and the connecting pipes are often made with connectors or quick connectors. Also, with the demand in recent years for low gasoline transpiration, minute gasoline transpiration from the connection sections such as the rubber hoses or the resin tubes, the one-way valves, and the like must now be controlled. Thus, the number connection points between structural elements must be reduced to lower gasoline transpiration.
One prior art proposal for reducing connection points between structural elements as well as reducing the number of parts in the evaporation tubing, a one-way valve or a check valve is either mounted internally in or added to a quick connector equipped with an insertion section for connecting pipes.
U.S. Pat. No. 6,397,884 (U.S. '884) in FIG. 1 and column 8; lines 8-40 discloses a quick connector having a one-way valve or check valve internally or as an add-on. U.S. '884's connector housing has a tube connection section formed on a first axial end and a pipe insertion section formed on a second axial end. A valve cap is formed integrally from a small-diameter section and a large-diameter section is attached to cover a first axial end of the tube connection section. A main valve body is housed in this valve cap so that it can move in the axial direction, and this main valve body is biased toward the first axial side by a compression spring. The main valve body closes the fluid flow path by abutting a ring-shaped valve seat surface formed on the inner surface of the valve cap between the small-diameter section and the large-diameter section. The fluid flow path is opened when main valve body receives fluid pressure from the first axial side and moves away from the valve seat surface. See, U.S. '884, FIG. 1 and column 8, lines 8-40.
In this type of connector equipped with a valve, if the evaporation tube that is attached is a large-diameter tube, the tube connected to the tube connection section has a large diameter, and the tube connection section has a large diameter, a valve cap having a large inner diameter can be used, thus allowing the valve seat surface and the closing section of the main valve body to be formed with large diameters. This allows the necessary flow to be provided when the flow path is opened. However, if the evaporation tubing is a small-diameter tube, the tube connected to the tube connection section has a small diameter, and the tube connection section is formed with a small diameter, a valve cap with a small inner diameter must be used, and the valve seat surface (the inner perimeter side of the valve seat surface) formed between the small-diameter section and the large-diameter section will often have a smaller diameter than the through-path of the tube connection section. This restriction makes it difficult to provide the necessary flow when the flow path is open. Furthermore, with this type of connector equipped with a valve, the valve cap is connected and secured, e.g., by being pushed into or adhesed, to the tube connection section after the elements of the valve have been assembled in the valve cap. Thus, the production of the connector equipped with a valve becomes complicated.
In an example of a connector equipped with a valve that can provide adequate flow even when used with small diameter evaporation tubing and that is also easy to produce, a valve housing section is disposed between the tube connection section and the pipe insertion section. The valve housing section has an inner diameter adequately larger than that of the tube connection section and can house a large-diameter main valve body. A connector housing is formed with an inner diameter equal to the valve housing section or with an inner diameter that is slightly larger than the valve housing section. On a first axial side of the pipe insertion section, the connector housing is used to house the main valve body along with a compression spring in the valve housing section. In this type of connector, there is no direct support to provide a secure fit at the first axial side of the pipe insertion section when a small-diameter connection pipe is inserted into the pipe insertion section, so a cylindrical bushing is fitted to the first axial side of the pipe insertion section to fill the gap formed with the connection pipe. The valve seat surface that abuts the main valve body is formed on a first axial end of this bushing. In this connector equipped with a valve, the bushing with the valve seat surface, the main valve body, and the compression spring, which are elements of the valve, can all be placed in the connector housing from a second axial end opening of the pipe insertion section. Thus, housing connection operations such as pressing elements in, adhesing, or welding are not required, and the main valve body and the valve seat surface can be formed with large diameters and a high flow volume can be provided when the valve is open.
However, in this type of connector equipped with a valve, the valve seat surface is formed on the bushing fitted to the connector housing. Since the accuracy of valve functions is dependent on precise dimensions in the main valve body, the connector housing, and the bushing, as well as precision in the assembly of the bushing, care must be taken when producing parts and assembling the bushing. This makes the connector less efficient to produce.